This invention relates to a low-pressure mercury discharge device for generating black light radiations, and, more particularly, to a device that includes a filter to filter out visible light radiations that would otherwise be transmitted by the device.
A number of black light lamps have been developed in recent years. These lamps generally have a special glass envelope designed to filter out visible light. They are expensive because of the high cost of the special glass required and the susceptibility of the glass to breakage during lamp manufacture. Elimination of the need for the special glass will reduce the cose of the lamp substantially.